1. Field of the Invention
The present invention is directed to an electrodeposition process for depositing a composite plating comprising a precious metal having wear resistant particles therein and the resultant plated article. More particularly the invention is directed to an electroplated surface finish having wear resistant particles therein which is particularly useful as a surface finish for high reliability electronic connectors.
2. Description of the Related Art
The trend in today's electronic technology is for electronic connectors, e.g. connectors for integrated circuit devices to a printed circuit board, to keep getting smaller and have increasing numbers of contact elements. Consequently, the entry pressure when mating the contacts increases unless the spring forces are reduced. This can ultimately result in unwanted increased wear of the contacts as measured for example by either frictional forces or contact resistance as a function of wear cycles.
Composite plated coatings of various types are known in the plating field and other fields. For example, Henry et al., in U.S. Pat. Nos. 4,830,889 and Feldstein, in 5,721,055 describe the co-deposition of fluorinated polyethylene and nickel from an electroless nickel plating bath. Historically, electroless or auto catalytic plating has always been treated as a separate and distinct technology from that of electroplating, the latter requiring an electric current for deposition to take place. The plated articles as disclosed in Feldstein are textile spinning machinery parts. Henry et al. sets forth several general uses for such co-deposits. It should be noted that Henry et al. state that "fluorinated carbon has been co-deposited directly on the substrate surface in electroplating processes", however, no details or description of the process or the metals being deposited are given. Itoh et al., U.S. Pat. No. 5,103,637 is directed to a rocket engine combustion chamber with a surface comprising a metal matrix, such as nickel or copper alloys having heat resistant particles such as ceramic oxide particles dispersed therein. The surface is formed by electroplating. Further, Tsuchiya et al., U.S. Pat. No. 5,124,007 describes a composite electroplated nickel having particles such as silicon nitride, silicon carbide or tungsten carbide dispersed therein for use on piston rings.